题解 | #统计各个部门的工资记录数#
统计各个部门的工资记录数
http://www.nowcoder.com/practice/6a62b6c0a7324350a6d9959fa7c21db3
先关联 再分组
select
d.dept_no,
d.dept_name,
count(s.salary) sum
from
dept_emp de
inner join salaries s on de.emp_no = s.emp_no
inner join departments d on de.dept_no = d.dept_no
group by
dept_no
order by
dept_no;